Topic: Ambisonic mics --- has anyone here recorded any shows?

[live2496]

Not exactly ambisonics but probably interesting nonetheless: Dutch Concertzender is streaming surround in high quality (386 kbps) on the web with all kinds of music, including 'historic' quadraphonic material. I listen to their program via a 4-speaker setup somewhat similar to yours.

http://www.concertzender.eu/sr.php

Ralf

This is nice sound quality. When I click on the link it plays windows media player 9 in an applet. It seems to render down to stereo for my laptops default sound device. I'm not sure how to configure it otherwise. Maybe if I had a surround sound capable soundcard it would act differently (?)
 

[Gutbucket]

There's actually an English version here http://www.stud.tu-ilmenau.de/~proverdi/indexen.html

- Daniel

^^
Well, that's a bit more accurate. Thanks.

Ralf, that Concertzender stream seems interesting.  Live2496, it will downmix to 2 channel stereo unless you have a multichannel output soundcard.  I need to look for a USB one for my laptop with that capability since the little one I'm using can only pass surround as a DTS or AC3 encoded SPDIF stream.

[fotoralf.be]

This is nice sound quality. When I click on the link it plays windows media player 9 in an applet. It seems to render down to stereo for my laptops default sound device. I'm not sure how to configure it otherwise. Maybe if I had a surround sound capable soundcard it would act differently (?)

I suppose it would. I receive it direct (i.e. outside of the browser) under...

mms://livemedia.omroep.nl/concertzender-5channel

...with VLC-PLayer, use the E-mu 1616's DSP mixer to add the C and LFE channels to L and R, and then output the result through the 1616 as a 4-channel analog signal which can be fed directly to the discrete inputs of my surround receiver. 

Ralf

P.S.: Currently, only the Windoze version of VLC-Player decodes the Concertzender stream. The OSX and Linux versions don't.

[Nick's Picks]

I thought the proper ambesonic playback setup was a tetra speaker array setup just like the capsules
one up top (point of the pyramid) and the more around the bass.  Listener sits in the center.
no ??

[Gutbucket]

I thought the proper ambesonic playback setup was a tetra speaker array setup just like the capsules
one up top (point of the pyramid) and the more around the bass.  Listener sits in the center.
no ??

That would make sense, and is the simplest theoretically correct playback scenario for full 1st order ambisonics with height.  In my weak understanding, one of the cool things about ambisonic playback is that the system is not locked into the 'one channel for each speaker' paradigm of most every other scheme like 2 channel stereo, quad or 5.1. Depending on the capabilities of your decoder, you can use any number of symmetrically arranged speakers and the more available the better.  If discarding the 'Z' height information you'll get more of your money's worth if all the speakers you have are in the horizontal plane.  The simplest setup without height would be a square, and some decoders can adjust for a rectangle.  Michael Gerzon experimented with tetrahedral playback with 4 speakers in the very beginning, but I think he decided 4 wasn't enough and that 6 were much better, 8 better still for full ambisonics with height.  I found some great photos of one of his early tetrahedral speaker tests, with two speakers up on ladders but I can't find them now.  I thought they came from the MichaelGerzonPhotos site which has some great photos and information about the man and the early development of ambisonics. 

Here's the 1st tetrahedral ambisonic mic-

[Gutbucket]

Found just one of several lurking one on the HDD.  Notice the speaker on the ladder-

[Kewl]

I thought the proper ambesonic playback setup was a tetra speaker array setup just like the capsules

If the capsules were "directly" connected to speakers, it would be the way to go. But the capsules signals are converted to B-Format (the capsules direct signal is A-Format) which allow to feed any speaker setup.

- Daniel

[live2496]

I thought the proper ambesonic playback setup was a tetra speaker array setup just like the capsules
one up top (point of the pyramid) and the more around the bass.  Listener sits in the center.
no ??

Since the capsules are pointed toward corners of a room (so-to-speak) the audio has to be transformed into up-down, left-right, forward-backward (XYZ cartesian coordinates) from the original. It's sine and cosine arithmetic. That resulting format is called b-format.

You can listen to b-format using a decoder which adjusts the discrete channels based upon the number of speakers you have. Ideally the listener is equidistant from all speakers. Your speaker setup can be two dimensional (ie. all in the same plane). This is what I plan to do. It could double as a 5.1 system too.